Bilirubin is a yellow substance which is formed in the blood as a result of degradation of hemoglobin, and is the principal pigment of bile manufactured in the liver. It has been estimated that approximately 200-230 milligrams of bilirubin and its derivatives are formed each day in a healthy human adult by the degradation of hemoglobin within the liver, spleen and bone marrow.
The diagnostic significance of bilirubin is well established. For example, an excessive amount of bilirubin within the human body, referred to as jaundice, is recognized as evidence of a variety of disease conditions, particularly diseases of the liver. In addition, jaundice often occurs in new born infants whose liver is slow to begin normal function. Thus, to facilitatee early diagnosis of certain disease states and/;or to actively reduce bilirubin levels, a bilirubin specific enzyme would be very useful.
Enzymes shown to be specific for bilirubin have been partially purified and characterized from certain fungi, as described in U.S. Pat. No. 4,211,844 (issued July 8, 1980 to myself) and in the literature article by Mura and Tanaka, "A New Enzyme 'Bilirubin Oxidase' Produced by Myrothecium verrucaria MT-1", Agric. Biol. Chem., 45(10), pp. 2383-2384 (1981). However, the enzymes obtained from such sources, particularly from the mushrooms described in my patent, have rather low specific activity for bilirubin. Because of this low specific activity, larger quantities of enzymes are required to provide acceptable assay results. Furthermore, the fungi from which those enzymes are obtained are not always readily available in large quantities except at high expense.
Hence, it would be desirable to have an enzyme highly specific to degrading bilirubin and suitable for bilirubin assays, which enzyme is available from readily-available sources at relatively low cost.